and to give my gut feeling answer to the original question, I think it might possibly be the opposite, where big ppc customers might actually find their sites ranking higher... but that might just be coincidence, as everything else still has to be in order such as links etc (it would be too obvious and scandalous if high ad budget sites with zero backlinks outranked those that deserved to be higher in the organic results
I have seen sites with million dollar google ad budgets ranking high first page in the organic rankings, so that kind of backs up the thought that it shouldn't hurt you at all to spend money with google
